Patient discussion about sun block

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Q. what does a sun block cream do? and what are a UV rays?

A1It blocks out harmful Ultra violet rays from the skin as the previous entries have related; however it can also block your ability to produce vitamin D. If you live in a northerly area or one that receives limited sunlight, its recommended to get at least 15 minutes of sun a day (this is probably best done with minimal sunblock) and according to personnal sun sensitivity. Another thing to keep in mind is that sunblock works best if applied 20 minutes before sun exposure.
A2I define uv rays in term of skin care as your skin is regarding this subject. Sunlight consist of different wavelength's radiation. Among them ultra violet is one of the most dangerous for skin and invisible portion of light.
UV rays are further subdivided on the base of wave-length ranges.
these are uvb, uva and uvc rays.
uvb radiation has the wave lenght range 280 to 315 nm, whereas the uva radiations have the w-l range 315 to 400.
uva is found in huge quantity as compare to the uvb in sunlight. And burning and tanning effects of the sunlight is due to the uva.
uvb most harmful for skin and causes skin cancer by damaging DNA in skin.
A3UV rays are rays of light (essentially, a form of energy transmitted) that are beyond the spectrum we are able to see. These light rays can damage the skin, precipitating its aging and increasing the risk to skin cancer like squamous cell carcinoma and basal cell carcinoma (the relationship of sun exposure and melanoma hasn't been proven definitely).

Sunscreen blocks these rays and so prevents some of its deleterious effect, although it hasn't been proven definitely to reduce the incidence of skin cancer.

Remember that even in the shade these rays are still reflected from other surfaces, and that they penetrate through glass window.

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